In electrophotographic recording apparatus, an electrostatic latent image formed on a surface of a photosensitive member by an electrophotography process is developed by toner supplied from a development device, and is then transferred to a recording medium. In the development device of the electrophotographic recording apparatus, a toner cartridge (hereinafter referred to as a cartridge) is removably mounted to a development device main body, and toner is replenished by exchanging the cartridge.
As shown in FIG. 1, the development device 1 comprises a main body 2 and a cartridge 3. As shown in FIG. 3, the main body 2 comprises a cartridge mounting part (hereinafter referred to as mounting part) 4, a toner supply roller 5 and a housing 6. In the mounting part 4, rotating members 8 and 9 which rotate in directions indicated by arrows B-C are provided, having an axis 7 of rotation with respect to the housing 6 and facing each other. The rotating members 8 and 9 are provided with levers 8a and 9a and joint grooves 8b and 9b, respectively. A shutter member 10 formed of polyethylene film or the like is provided to span across the rotating members 8 and 9 and is fixed to parts (positioned at the bottom in the state shown in FIG. 1) of the circumferential edges of the members 8 and 9, to block an opening 11 at the bottom of the mounting part 4, as shown in FIG. 2. As shown in FIG. 4, the cartridge 3 comprises a cylinder 12 and revolving members 13, 14 provided at opposite end openings of the cylinder 12, a stopper 15 fixed to the center of the cylinder 12, and toner 16 shown in FIG. 2. The cylinder 12 comprises an outer cylinder 17, and an inner cylinder 18 which is coaxial with the outer cylinder 17, has its outer surface slidably abutting against the inner surface of the outer cylinder 17, and is therefore slidable against the outer cylinder 17. The outer and inner cylinders 17 and 18 are provided with openings 17a and 18a along part only of their circumference. The revolving members 13 and 14 are fixed to close the opposite end openings of the inner cylinder 18. Provided integrally with the revolving members 13 and 14 are linear joint projections 13a and 14a which engage with the joint grooves 8b and 9b on the rotating members 8 and 9. The stopper 15 extending semi-circularly along the outer side of the outer cylinder 17 is fixed to the central part of the outer cylinder, and its opposite ends 15a and 15b are in abutment with edges 6a and 6b of the casing 6 of the mounting part 4.
Operation will now be described. First, as shown in FIG. 3, the levers of the rotating members 8 and 9 are rotated in the direction of arrow C. The rotating members 8 and 9 stop when they abut with stoppers, not shown. At this moment, the joint grooves 8b and 9b are vertical. The cartridge 3 is placed such that its axis is parallel with the axis of the mounting part 4, and is pressed in, with the joint projections 13a and 14a being engaged with the joint grooves 8b and 9b. The cartridge 3 is thus set in the main body 2, as shown in FIG. 1. The bottom part of the cartridge 3 is in contact with the shutter member 10, as shown in FIG. 2, and the ends 15a and 15b of the stopper 15 abut against the edges 6a and 6b of the casing 6. Then, with the outer cylinder 17 being pressed, the levers 8a and 9a of the rotating members 8 and 9 are rotated in the direction of arrow B shown in FIG. 3. Since the joint projections 13a and 14a of the cartridge 3 are engaged with the joint grooves 8b and 9b of the rotating members 8 and 9, the revolving members 13 and 14 are rotated in the direction of arrow B. The inner cylinder 18 fixed to the revolving members 13 and 14 is therefore rotated in the direction of arrow B. The shutter member 10 fixed to the rotating members 8 and 9 is also rotated in the direction of arrow B. On the other hand, since the end 15a of the stopper 15 fixed to the outer cylinder 17 is in abutment with the edge 6a of the casing 6 as shown in FIG. 2, the outer cylinder 17 is not rotated.
When the opening 18a of the inner cylinder 18 comes to the position at which it overlaps or aligns with the opening 17a of the outer cylinder 17, the levers 8a and 9a abut against stoppers, not shown, and stop. The shutter member 10 also rotates, together with the rotating members 8 and 9, in the direction of arrow B and the opening 11 at the bottom of the mount part 4 is unblocked. The toner 16 that is contained in the inner cylinder 18 passes through a toner opening comprising the openings 18a, 17a and 11 and is supplied to the main body 2.
For removing the cartridge 3 from the mounting part 4, the levers 8a and 9a of the rotating members 8 and 9 are rotated in the direction of arrow C as shown in FIG. 3 until abutment with stoppers, not shown. The inner cylinder 18 rotates with the rotating members 8 and 9 in the direction of arrow C, and the opening 18a of the inner cylinder 18 completely ceases to overlap the opening 17a of the outer cylinder 17. The shutter member 10 blocks the opening 11, and the toner opening is blocked. Then, the joint grooves 8b and 9b of the rotating members 8 and 9 are vertically aligned, so the cartridge 3 can be removed from the mounting part 4.
In the cartridge mounting/removal mechanism in the related art development device, the inner cylinder 18 slides in contact with the outer cylinder 17, so a frictional force is created in the direction of the tangent of the abutting circumferential surfaces. For instance, for supplying the toner in the cartridge to the main body, the inner cylinder 18 is made to slide, as shown in FIG. 5, in the direction of arrow B while in contact with the inner surface of the outer cylinder 17. At the points of sliding D and E between the outer cylinder 17 and the inner cylinder 18, frictional forces F act on the inner cylinder 18 in the directions of tangents as indicated by the solid line arrows, whereas reactive force F' which are equal to but opposite to the frictional forces F act on the outer cylinder 17, as indicated by broken line arrows. As a result, a moment acts on the cartridge at the sliding points D and E, about an abutment point G between the end 15a of the stopper fixed to the outer cylinder 17 and the edge 6a of the casing 6. If the distances from the abutment point G to the sliding points D and E are denoted by L1 and L2, at the sliding points D and E, the outer cylinder 17 receives moments F'.times.L1, and F'.times.L2, respectively. The difference M in the moment: EQU M=F'.times.L1-F'.times.L2
acts on the cartridge as a rotary moment, tending to rotate the cartridge in the direction of arrow H. Actually, the sum of all the rotary momemts over the entire sliding surfaces determines the net effect.
When the cartridge 3 is removed from the mounting part 4, the inner cylinder 18 is rotated in the direction of arrow C, so for a reason similar to that described above, a moment in the direction of arrow J acts on the cartridge about an abutment point I between the end 15b of the stopper 15 and the edge 6b of the casing 6.
Since the rotating members 8 and 9 of the main body 2 and the revolving members 13 and 14 of the cartridge 3 are engaged by linear grooves and projections, when a rotary moment acts, the cartridge not only rotates in the direction of arrow H or the arrow J, but also is lifted. When the cartridge 3 is lifted, toner is scattered, and the main body 2 is soiled. In order to prevent the lifting of the cartridge 3, the operator must press the cartridge 3 when he rotates the lever of the main body. This is achieved for instance by pressing the cylinder 12 with his thumb and simultaneously rotating the lever with his forefinger. If the cylinder of the cartridge 3 is pressed with the thumb, since the cylinder is thin, it is deformed, and the inner cylinder becomes difficult to rotate.